1. Field of the Invention
The present invention relates to an optical disc recording method and apparatus, and more particularly, to a write control method, which varies write power in response to a recording speed, a recording density, and a type of recording medium, and an optical disc recording apparatus suitable for the write control method.
2. Description of the Related Art
Recording media with high capacity are necessary in the multimedia age, and optical recording apparatuses using the recording media with high capacity include a magnetic optical disc drive (MODD), a compact disc (CD) recording apparatus, a CD Rom/ReadWrite (CD-R/RW) recording apparatus, a digital versatile disc (DVD) recording apparatus, and a DVD Random Access Memory/ReadWrite (DVD-RAM/RW) recording apparatus.
In these optical recording apparatuses, since the available time for forming a record mark with the same length decreases as a recording speed increases, an increasingly more precise write control is required corresponding to the increase of the recording speed.
In general, in an optical disc, a signal is recorded by heating a recording layer with a laser beam or by cooling the recording layer with natural cooling. A crystalline state of the recording layer is affected by a heating temperature and a cooling speed, and crystalline and amorphous states of this recording layer correspond to values (0 and 1) of a binary signal, respectively.
The heating temperature for the recording layer is influenced by write control including the write power and a heating period of the laser beam. That is, a record mark with a desired length can be formed by radiating a laser beam with a predetermined write power on the recording layer for a predetermined heating period.
However, when the record marks with identical lengths are formed, if the recording speed is changed, that is, if the heating period is changed, the amount of heat accumulated in the recording layer changes. Accordingly, inequality of the recording, and more particularly, jitter is generated where starting and ending positions of the record marks drift. This inequality of the recording is also generated when a recording density is changed, that is, when lengths of the record marks with the same pattern (for example, 3T, 4T, etc) changed.
Accordingly, an improved write control method which varies write control so that heat accumulation on the recording layer can be accurately performed in response to a change of the recording speed and the recording density is required.